Desalination 222 (2008) 128–134 Presented at the conference on Desalination and the Environment. Sponsored by the European Desalination Society and Center for Research and Technology Hellas (CERTH), Sani Resort, Halkidiki, Greece, April 22–25, 2007. 0011-9164/06/$– See front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.0000.00.000 The application of hybrid system UASB reactor-RO in landfill leachate treatment Jolanta Bohdziewicz a , Anna Kwarciak b * a Silesian University of Technology, Institute of Water and Wastewater Engineering, ul. Konarskiego 18, 44-100 Gliwice, Poland b Technical University of Czestochowa, Institute of Environmental Engineering, ul. Brzez ´nicka 60, 42-200 Cze g stochowa, Poland Tel. +48 343250-917; Fax +48 34325-04-61; email: akwarciak@is.pcz.czest.pl Received 20 December 2006; accepted 7 January 2007 Abstract The aim of the paper was to study landfill leachate treatment efficiency during fermentation process in UASB reactor and post-treatment in RO process. In the first step of experiment, the granular sludge was acclimatized to treatment with high loaded synthetic wastewater. Next, the optimal concentration of raw leachate in synthetic wastewater was determined (5% v/v–40% v/v). At this stage, UASB reactor was operated at hydraulic retention time (HRT) of 7 days and organic loading rate (OLR) of 0.6 kg COD × m -3 d -1 . While the optimal concentration of raw leachate in synthetic wastewater (20% v/v) was determined, the HRT was shortened from 7 to 2 days with a increase of OLR from 0.6 to 2.0 kg COD × m -3 d -1 . The HRT (3 days) and OLR 1.3 kg COD × m -3 d -1 were taken as the optimum fermentation process parameters. Under such designed conditions COD removal achieved value of 76%. The concentration of COD, BOD, ammonia nitrogen, chloride concentration in effluent was kept on the level of 960 mg O 2 × dm -3 , 245 mg O 2 × dm -3 , 196 mg NH 4 + × dm -3 and 2350 mg Cl - × dm -3 respectively. Due to poor quality of UASB effluent, wastewater was put into the post-treatment process. In RO process COD, BOD, chloride, ammonia nitrogen parameters were removed in 95.4%, 90.2%, 85.4% and 88.7% respectively. Keywords: Landfill leachate; UASB reactor; Hydraulic retention time; Organic loading rate; Reverse osmosis 1. Introduction Landfill has been the most economical and environmentally acceptable method for the dis- posal of solid waste throughout the world. Up to 95% of solid waste generated worldwide is cur- rently disposed in landfills [1–3]. After landfilling, the solid waste, undergoes physico-chemical and biological changes. Municipal solid waste (MSW) produces leachate and gas emissions during decomposition process [4,5]. Landfill leachate is a wastewater, formed in a result of percolation of *Corresponding author.